The problem of basement flooding from sewer line water backup has become prevalent in recent years. This backup problem obviously occurs when the flow capacity of a sewer system is exceeded by the rain water in-flow rate into the system. The risk of water backup is present in most storm sewer systems where the storm sewers are rarely of a sufficient size to accommodate unusually heavy rainstorms. This risk is sometimes present in a sanitary sewer system where there is water leakage into the sewer line through manholes, cracks in sewer line joints or where improper roof downspout connections are made to the system which normally should only carry the water and sewage draining from sinks, toilets, washing machine drain lines and basement floor drains.
Backup problems in sanitary sewer lines leading to an individual home can be substantially eliminated by the application of a back flow preventing valve in the pipeline extending between the home and the underground sanitary sewer line running along the street involved. When backup water pressure builds up, the back flow preventing valve is closed or closes to prevent the water in the sanitary sewer line from backing up into the user's home. Of course, the downspouts of the user's home where such a backup valve is installed must not be connected to the pipe leading to the sanitary sewer or else the owner's own downspout rain water would create a backup problem in the owner's home. However, many home owners simply do not wish to incur or cannot afford the cost of such a backflow preventing valve installation.
Most homes have drain tile at their foundation footings and outside drains which collect rain water directed through pipes leading to the storm sewer line running underground along the street involved. A backflow preventing valve placed in the pipeline leading from the street storm sewer line to these rain water collection points of a home would not alleviate a basement flooding hazard because the water collected in these drain tiles and outside drains and downspouts would build up behind a closed backflow preventing valve to cause a flooding problem.
To minimize backup problems from a storm sewer system, a number of expensive methods have been heretofore proposed. Where there are adequate spaces and tax revenues available for doing so, water drainage ponds and lakes have been constructed to collect excess rain water run-off before the water can gain direct access to the storm sewer system. Such drainage ponds or lakes are usually not feasible. Moreover, recently it has been discovered that such drainage ponds and lakes have created drinking water contamination problems if the area obtains its drinking water from underground wells or streams into which the water in the drainage ponds and lakes can drain.
Storm sewer backup can also obviously be minimized by increasing the size of the storm sewers making up a citywide storm sewer system. However, this is obviously an extremely expensive and usually impractical solution to the problem, unless the storm sewer system has to be replaced for other reasons.
The present invention in its most useful form presents a unique approach to minimizing water backup problems in both sanitary and storm sewers on an area-wide basis, encompassing large numbers of homes along streets many blocks long, and at a small fraction of the cost of replacing the sewer systems involved.